Foam-forming flame-extinguishing compositions containing alkylpolyalkoxysulfates, polyoxyethylene resin and symmetrical dibromotetrafluoroethane

ABSTRACT

A foam-forming flame-extinguishing composition containing an aqueous solution of a water soluble alkylpolyalkoxy-sulfates, preferably in combination with a polyoxyethylene resin and advantageously, with symmetrical-dibromotetrafluoroethane.

United States Patent Rainaldi et al.

} [451 Aug. 15,1972

1541 FOAM-FORMING FLAME- EXTINGUISHING COMPOSI'IIONS CONTAININGALKYLPOLYALKOXYSULFATES, POLYOXYETHYLENE RESIN AND SYMMETRICALDIBROMOTETRAFLUOROETHANE [72] Inventors: Nicolino Rainaldi, 6, Via PorteNuove-Mestre; Pierluigi Fatutto, 2091, Via Dorso Duro, both of Venezia,Italy [22] Filed: Jan. 25, 1971 [21] Appl. No.: 109,620

Related US. Application Data [63] Continuation-impart of Ser. No.827,959, May

26, 1969, Pat. No. 3,609,074, and a continuation-in-part of Ser. No.83,603, Oct. 23, 1970.

[30] Foreign Application Priority Data Jan. 27, 1970 Italy 19827 A/70Jan. 29, 1970 Italy ..19921 N70 52 U.S.Cl ..l69/lA,252/3,252/8, 252/805,252/307 51 1m. (:1. ..A62d 1/00 58 FieldofSearch..252/3,8.05,307,8;169/1A Polyox Water Soluble Resins, Union CarbideCompany, New York, 1968 P. 1- 4.

Primary Examiner-Robert F Burnett Assistant Examiner-D. J. FritschAttorney-Karl F. Ross [57] ABSTRACT A foam-forming flame-extinguishingcomposition containing an aqueous solution of a water solublealkylpolyalkoxy-sulfates, preferably in combination with apolyoxyethylene resin and advantageously, withsymmetrical-d1bromotetrafluoroethane.

6 Claims, No Drawings FOAM-FORMING FLAME-EXTINGUISHING COMPOSITIONSCONTAINING ALKYLPOLYALKOXYSULFATES, POLYOXYETHYLENE RESIN ANDSYMIVIETRICAL DIBROMOTETRAFLUOROETHANE CROSS REFERENCE TO COPENDINGAPPLICATIONS The present application is a continuation-in-part of ourco-pending application Ser. No. 827,959 filed 26 May 1969 (now U.S. Pat.No. 3,609,074, issued 28 Sept. 1971) and a continuation-in-part of ourapplication Ser. No. 83,603, filed 23 Oct. 1970 as acontinuation-in-part of application Ser. No. 827,959.

FIELD OF THE INVENTION Our present invention relates to foam-formingflameextinguishing compositions and, more particularly, toflame-extinguishing compositions particularly adapted to quench,extinguish or confine fires fueled by hydrocarbons.

BACKGROUND OF THE INVENTION for It has been proposed heretofore toextinguish fires by various techniques based generally upon exclusion ofoxygen from the combustion site, abstraction of heat from the combustionsite or physical elimination of the flame from a fuel substance.Considerable effort has been expended upon developing foam-formingflameextinguishing compositions of this purpose since the foam functionsas a mechanical barrier to the transport of oxygen to the combustionsite, covers the fuel to prevent or limit ignition, and providessubstances of high heat capacity for removal of heat from the source ofcombustion. For the most part, such foam-forming compositions have beenfound to require an aqueous medium, a foam-stabilizing or foam-producingsurfactant and a propellant.

However, such foam-forming flame-extinguishing compositions have beeninadequate for extinguishing fires fueled by hydrocarbons as may developat industrial installations, refineries, tank farms and with the like,and burning hydrocarbons on water.

THE DISCLOSURE OF THE CO-PENDING APPLICATIONS In the aforementionedco-pending applications, we have described flame-extinguishingcompositions constituting improvements over the prior art systems andhaving greater foam stability, and ability to extinguish fires onhydrocarbons more rapidly, the capability of preventing flashback (i.e.re-ignition of a combustible substance covered by the foam) etc.

In application Ser. No. 827,959, for example, we have described aflame-extinguishing foam-forming liquid composition which contains oneor more fluorobromoalkanes in addition to the substances commonlyprovided in flame-extinguishing foams. Such substances included water,emulsifying and foam-stabilizing surface active agents, propellants andfoaming agents, antifreezing agents capable of lowering the freezingpoint of the composition, buffering agents, corrosion inhibitors andthickening and carrying agents. The fluorobromoalkanes which wereemployed,

in an amount of 5 to 25 percent by weight of the composition, were thebromine-containing halogen-satu rated alkanes of low carbon number, eghaving one to six carbon atoms in the main chain.

As pointed out in this application, best results are obtained withcompounds containing at least four fluorine atoms and at least twobromine atoms per molecule and preference was given tosymmetricaldibromotetrafluoroethane, l ,2-dibromo- 1 1 2 ,2-tetrafluoroethane. In that application, we have also pointed out thatthe surface-active agents have been found to be most suitable as theorganic sulfonates and sulfates, alkylarylpolyethyleneglycol ethers,esters of alcohol such as sorbitol with higher fatty acids such aslauric, stearic, palrnitic acids, sodium or ammonium salts orsulfocarboxylic acids such as dialkylsulfosuccinic acid with up to eightcarbon atoms in each alkyl group.

In our later application Ser. No. 83,603, we further pointed out thatthe composition can be improved by associating with thebromofluoroalkane a foaming agent of the ammonium alkylpolyalkoxysulfatetype to produce a binary combination with the bromofluoroalkane. Thebinary combination, used as an aqueous solution or dispersion, providedmarkedly improved results. It appeared that the result is a consequenceof some association of the ammonium alkypolyalkoxysulfate and thebromofluoroalkane which yields a more stable form (against heat andmechanical disruption) than is obtainable when the bromofluoroalkane isused with other foaming agents and also of greater stability than foamsusing the ammonium polyalkoxysulfate in association with, say,chlorofluoroalkanes in equivalent quantities. Equally surprising was thefact that the improvement was particularly marked when thefluorobromoalkane was the 1 ,2- dibromotetrafluoroethane mentionedearlier. Best results were found to be obtained when the foaming agentwas ammoniumlaurylpolyethoxysulfate, the polyethoxy group having two to30 ethoxy units.

OBJECTS OF THE INVENTION It is the principal object of the presentinvention to provide an improved foam-forming flame-extinguishingcomposition capable of rapidly extinguishing flames, especially ofhydrocarbon fires, with a minimum of flashback and a maximum of foamstability.

It is another object of the invention to extend the principlesoriginally set forth in the above-mentioned co-pending applications tofoam-forming flame-extinguishing compositions of an improved nature.

SPECIFIC DESCRIPTION We have now discovered, most surprisingly, thatalkylpolyalkoxysulfate in the form of water-soluble salts, constituteexcellent flame-extinguishing substances in their own right, especiallywhen dispersed as a foam upon a hydrocarbon fire. Advantageously, thealkylpolyalkoxysulfate is used as an ammonium salt, possesses ethoxygroups in a chain of two to 30 ethoxy groups and has an alkyl group witheight to 22 carbon atoms, preferably 12-14. Best results are obtainedwith ammonium]aurylpolyethoxysulfate.

We have further found that ammoniumlaurylpolyethoxysulfate actssynergistically or symbiotically with water-soluble high molecularweight polyoxyethlene resins in creating flame-extinguishing foams underthe action of a blowing agent or propellant. Surprisingly, thefire-fighting properties of a water-soluble surface active substancecapable of generating foam under the action of a blowing agent,especially the ammoniumalkylpolyalkoxysulfate, are greatly improved bythe addition to the solution of the water-soluble high-molecular weightpolyoxyethylene resin.

We have found, moreover, that the flame-extinguishing activity of acomposition containing both the amoniumalkylpolyalkoxysulfate and thehigh molecular weight polyoxyethylene resin is improved still further bythe addition of a symmetricaldibromotetrafluoroethane as a third activecomponent.

It is self-understood that compositions of the present invention mayalso contain propellants, dispersing agents and other conventionaladjuvants, such as corrosion inhibitors and anti-freezing agents, in theamounts and of the type described in the aforementioned copendingapplication.

A preferred subgroup of water-soluble alkylpolyalkoxysulfate is theammonium salts of alxylpolyethoxy sulfuric acids in which the alkylradical contains 12 to 14 atoms in the main chain and the number ofethoxy groups is two to 30 as noted earlier. Because theammoniumalkylpolyalkoxysulfates generally have peculiar foamingcharacteristics, it has been found to be advantageous to use theammonium salt of lauryltriethoxysulfate, commonly in the form of a watersolution containing 10 percent by weight of the active substance.

The polyoxyethylene resin is a polymer having 7,000 to 200,000oxyethylene units per molecule, an average molecular weight of 250,000to 8,000,000, and a viscosity of 5,000 to 8,000 cps in an 0.5 to 5percent aqueous solution.

The liquid composition of the present invention may comprise the threeactive components individually or in combination, together making up 2to 70 percent by weight of the composition, the balance being water andadjuvants as noted earlier. When ammoniumlauryltriethoxysulfate and thepolyoxyethylene are used together, they are present in a ratio by weightof 2 to 0.5 while dibromotetrafluoroethane may be employed in an amountof 3.5 to 35 times the total weight of the ammonium salt and thepolyoxyethylene resin.

Preferably, the flame-extinguishing material has the followingcomposition:

1-10 percent by weight of a 10 percent aqueous solution oflauryltriethoxysulfate;

l-l percent by weight of a 0.5 to percent aqueous solution ofpolyoxyethylene resin of a viscosity between 5,000 and 8,000 cps and anaverage molecular chain containing 7,000 to 200,000 oxyethylene units;

0-70 percent by weight dibromotetrafluoroethane; and

-98 percent water.

Substantially any technique may be used for dispensing the compositionof the present invention. The composition may be projected onto the firesite with conventional foam-throwing apparatus to which the componentsof the composition are fed separately and are combined at the nozzleunder the action of the propellant or blowing agent. It has been foundthat, for practical use in mobile fire-extinguishing installations,

a mixture containing an aqueous solution ofammoniurnlaurylpolyethyoxysulfate and the polyoxyethylene resin shouldbe provided in one tank while the dibrotetrafluoroethane is supplied inanother tank, the contents of the tanks being fed to the foam-projectingnozzle together with a blowing agent such as carbon dioxide or one ofthe other propellants set forth in the above-identified co-pendingapplication.

SPECIFIC EXAMPLES EXAMPLE I A rectangular metal container 8 X 5 meters,25 cm deep, was filled with water to a height of 10 cm; over this waterlayer 260 liters of gasoline and 140 liters of kerosene were poured.

The fuel was ignited and pennitted to burn; after 60 seconds ofprecombustion, a single operator began to extinguish the fire with anaqueous foam-forming composition. The fire was completely extinguishedwithin 60 seconds.

The extinguishing composition was a 20 percent solution of foamingagents based on ammoniumlaurylpolytriethoxysulfate, commercially knownas METEOR-HIEX-MR-ZOO, a trademark of Svenskaa Skumslacknings A.B.

13.8 kg of this solution was used during the extinguishing of the fire,projected from a tank of a mobile fire-extinguishing installationthrough a normal firemans nozzle together with 186.2 liters of water, ata pressure of 4 atm, under blowing with air.

The expansion ratio (liters of foam generated by 1 liter of the finalaqueous solution, which is now 0.6 percent by weight inammoniumlauryltriethoxysulfate) was 1:10.

EXAMPLE II Under the same operative conditions of Example I, after 40seconds of precombustion, the fire was completely extinguished within 50seconds, with a fireextinguishing composition prepared by admixing,under blowing with air (expansion ratio 1:10) 2 volumes of an aqueoussolution consisting of:

1 volume of a 20 percent aqueous solution of foaming agents based onammoniumlaurylpolyethoxysulfate volume of a 5 percent aqueous solutionof a polyoxyethylene resin having the molecular weight of 250,000 to8,000,000 and the viscosity range from 5,000 to 8,000 cPs (this solutionis commercially known as POLYOX-WRS-750, a trademark of the UnionCarbide Company) 20 volumes of water. The consumption of the aqueoussolution was 4.1 liters (plus 410 liters of water).

EXAMPLE III Example I was repeated, but with a mixture of 400 liters ofgasoline and liters of kerosene as the fuel. The fuel was ignited andlet burn for 60 seconds; after this precombustion period, the fire wasput out within 23 seconds, using the following liquid composition:

a) 1,2-dibromo-l ,1 ,2,2-tetrafluoroethane kg 1 6 (propelled from aseparate tank of the mobile fire-fighting installation b) an aqueoussolution kg0.86

consisting of 1 volume of a 20% aqueous solution of foaming agents basedon ammonium laurylpolyethoxysulphate 1 volume of a 5% aqueous solutionof polyoxyethylene resin (propelled from a separate tank of the mobilefire-fighting installation) water c) kg8.6

The flame-extinguishing composition was blown under pressure with air,maintaining an expansion ratio of 1:10.

EXAMPLE lV a) l ,Z-dibromo- 1 l ,2,2-tetrailuoroethane kg8 b) aqueoussolution of the two components cited in Example 111, 1:1 by volume kg2.2c) water kg22 extinguished the tire within 22 seconds (expansion ratio,as previously defined, 1:10).

EXAMPLE V Example III was repeated. After 60 seconds of precombustion,the fire was put out within 32 seconds using the following mixture:

1,2-dibromol l ,2,2-tetrafiuoroethane aqueous solution of foaming agentsbased on ammonium a) kg24.4

laurylpolyethoxysulphate water kg7.ll kg] 10.

We claim:

1. A flame-extinguishing foam-forming composition comprising as activefire-extinguishing components, 1 ,2-dibromotetrafluoroethane,ammoniumlauryltriethoxysulfate and a polyoxyethylene resin, in aqueoussolution, of an average molecular weight of 250,000 to 8,000,000.

2. The composition defined in claim 1 wherein the ratio by weightbetween said ammonium lauryltriethoxy-sulfate and said polyoxyethyleneresin ranges between 2 and 0.5.

3. The composition defined in claim 2 wherein said polyoxyethylene resinhas a viscosity in 0.5 to 5 percent aqueous solution of 5,000 to 8,000cPs.

4. The composition defined in claim 3 wherein said polyoxyethyleneresin, said ammoniumlauryltriethoxysulfate and said1,2-dibromotetrafluoroethane are present in an amount of 2 to percent byweight of the composition.

5. The composition defined in claim 4 consisting essentially of l to 10percent by weight of a 10 percent aqueous solution ofarnmoniumlauryltriethoxysulfate, 1 to 10 percent by weight of a 0.5 to 5percent aqueous solution of said polyoxyethlene resin, 2 to 70 percentby weight 1,2-dibromotetrafluoroethane, and 10 to 98 percent by weightwater.

6. A method of extinguishing a hydrocarbon fire, comprising the step ofprojecting the foaming composition defined in claim 5 thereupon.

we UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTEON Patent NO.3,684,018 Dated 7 S ptem er 1912 Inventor s It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below;

In the heading, prior to line insert L133 Assignee: mm-nca'um mnxsou s..A..

A Milano, ITALY Signed and sealed this 3rd day of April 1973 (SEAL)Attesc:

EDWARD M. PLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

2. The composition defined in claim 1 wherein the ratio by weightbetween said ammonium lauryltriethoxy-sulfate and said polyoxyethyleneresin ranges between 2 and 0.5.
 3. The composition defined in claim 2wherein said polyoxyethylene resin has a viscosity in 0.5 to 5 percentaqueous solution of 5,000 to 8,000 cPs.
 4. The composition defined inclaim 3 wherein said polyoxyethylene resin, saidammoniumlauryltriethoxysulfate and said 1,2-dibromotetrafluoroethane arepresent in an amount of 2 to 70 percent by weight of the composition. 5.The composition defined in claim 4 cOnsisting essentially of 1 to 10percent by weight of a 10 percent aqueous solution ofammoniumlauryltriethoxysulfate, 1 to 10 percent by weight of a 0.5 to 5percent aqueous solution of said polyoxyethlene resin, 2 to 70 percentby weight 1,2-dibromotetrafluoroethane, and 10 to 98 percent by weightwater.
 6. A method of extinguishing a hydrocarbon fire, comprising thestep of projecting the foaming composition defined in claim 5 thereupon.